Wow...9 1/2 week old chicks indoors? I imagine that IS ripe! 
Another option is biochar, which is just charcoal. You could but a bag of lump (not briquette) charcoal, and crush some fairly fine and mix with the bedding. I’ve found it’s great at absorbing odors (although it is black so a bit dirty).
My favorite crushing method is a plastic bucket and a scrap of lumber (think mortar and pestle).
The good news is that if the chicks did consume any biochar, it’s at worst neutral and likely beneficial to their digestive tracks.

Another option is biochar, which is just charcoal. You could but a bag of lump (not briquette) charcoal, and crush some fairly fine and mix with the bedding. I’ve found it’s great at absorbing odors (although it is black so a bit dirty).
My favorite crushing method is a plastic bucket and a scrap of lumber (think mortar and pestle).
The good news is that if the chicks did consume any biochar, it’s at worst neutral and likely beneficial to their digestive tracks.